1. Field of the Invention
The invention relates to an image-blur compensating device configured to compensate blurred images due to, for example, unintentional movements of a user's hand holding a so-called image-blur compensation image pick up apparatus, and also to an image pickup apparatus having the image-blur compensating device such as digital still cameras or camcorders.
2. Description of the Related Art
When a user unintentionally moves her/his hand in capturing images using a related art digital still camera or camcorder, the captured images are blurred in response to hand trembling or wobbling, thereby significantly deteriorating the quality of the captured images. There are roughly two technologies to compensate the image-blur of this kind, namely, optical compensation technology, and electrical compensation technology in which the blurred images captured by an imager are electrically compensated.
In the optical compensation technology, an optical component is placed in a point of an optical path of an image light that passes thorough an optical pickup lens to reach an imager so that an optical axis of the image is compensated. As a result, the image-blur resulting from unintentional hand movements that have affected the image pickup device is compensated to obtain a stabilized image.
FIG. 1 is a block diagram illustrating a configuration of an image compensating device according to the related art image pickup apparatus. The image pickup apparatus includes an optical system for capturing images having a main lens 41, a shift lens 42, and a focus lens 43 that are arranged along an optical axis Z, and light of images is incident on an imaging surface of an image pickup device 44 via the optical system having these lenses. The image pickup device 44 then converts the incident light of the images into an electrical image signal. The shift lens 42 is utilized for compensating a blurred image. The shift lens 42 can be tilted in a pitch angle direction by driving a pitch actuator 32, and can also be tilted in a yaw angle direction by driving a yaw actuator 36. The pitch and yaw angles are used for tilting the shift lens 42 horizontally, and formed with two mutually different directions intersecting at right angles to an optical axis Z and having an angle of 90 degrees therebetween. The pitch and yaw angles of the shift lens 42 are detected by pitch and yaw position sensors 33, 37, detected output signals of which are converted into digital data by analog-to-digital converters 34, 38, and the digitized data are supplied to a servo calculator 22.
The image pickup apparatus also includes an angular velocity sensor 11 detecting an angular velocity applied from outside to the image pickup apparatus in a pitch angle direction, and a yaw velocity sensor 14 detecting an angular velocity applied from outside to the image pickup apparatus in a yaw angle direction. The “unintentional movements” affected on the image pickup apparatus can be detected by the angular velocity applied to the two directions, namely, the pitch angle direction and yaw angle direction.
The output signal detected by the pitch angle sensor 11 is amplified by an amplifier 12, digitized by an analog-to-digital converter 13, and then supplied to an image blur compensation calculator 21 in a control unit 20. The output signal detected by a yaw angle sensor 14 is amplified by an amplifier 15, digitized by an analog-to-digital converter 16, and then supplied to the image blur compensation calculator 21. The image blur compensation calculator 21 calculates compensation amounts of pitch angle and yaw angles, and transmits the obtained compensation amounts to the servo calculator 22.
The servo calculator 22 calculates target pitch and yaw angles based on the compensation amounts of pitch and yaw angles supplied thereto, and then generates pitch and yaw driving signals resulted from the obtained pitch and yaw angles. The pitch and yaw driving signals are supplied to digital-to-analog converters 31, 35, respectively. The driving signals converted by the digital-to-analog converters 31, 35 are supplied to the pitch actuator 32 and the yaw actuator 36 to thereby set the pitch and yaw angles of the shift lens 42 in compliance with the obtained driving signals.
FIG. 2 is a block diagram illustrating a more detailed configuration example of pitch and yaw angle settings for the image compensating device according to the related art. A pitch angle compensation amount Tp output by the control unit 20 calculating the image compensation amount is supplied to a subtracter 51, so that the difference between the supplied pitch angle compensation and a current pitch angle is detected. The detected difference is supplied to a PID control operation unit 52 to generate a driving signal for the pitch actuator, and the generated driving signal is supplied to the pitch actuator 32 via the digital-to-analog converter 31. The pitch portion of the shift lens driven by the supply of the driving signal is detected by the pitch position sensor 33, and the detected pitch position of the sensor 33 is converted by the analog-to-digital converter 34 via an amplifier 53. The converted pitch position is supplied to the subtracter 51 to calculate the difference between the pitch angle compensation amount Tp and the converted pitch position supplied.
A yaw angle compensation amount Ty output by the control unit 20 is supplied to a subtracter 54, so that the difference between the supplied yaw angle compensation value and a current yaw angle is detected. The detected difference is supplied to a PID control operation unit 55 to generate a driving signal for the yaw actuator, and the generated driving signal is supplied to the yaw actuator 36 via the digital-to-analog converter 35. The yaw portion of the shift lens driven by the supply of the driving signal is detected by the yaw position sensor 37, and the detected yaw position of the sensor 37 is converted by the analog-to-digital converter 56 via an amplifier 38. The converted yaw position is supplied to the subtracter 54 to calculate the difference between the pitch angle compensation amount Tp and the converted yaw position supplied.
The pitch angle and yaw angle of the shift lens are respectively compensated in compliance with the angular velocity applied to the image pickup apparatus in this manner to thereby compensate the image blur. Japanese Unexamined Patent Application Publication No. 2007-17874 discloses an example of an image-pickup apparatus having a shift lens of this kind.